Molding press head control system



NOV. 11, 1958 w FLOEHR 2,859,49Q

MOLDING PRESS HEAD CONTROL SYSTEM Filed Sept. 5, 1957 PEESSUEE SOURCE I44 I I 34 42 1 r 40 48 I 32 i 38 f I x 1 4 36 I l 46 4 g 0 4 i INVENTOR54 x, i o I '6 ilalferblloelw ATTORNEY Ice Patented Nov. 11, 1958MOLDING PRESS HEAD CONTROL SYSTEM Walter L. Floehr, Toledo, Ohio,assiguor to Unitcast Corporation, Toledo, Ohio, a corporation of 01110Application September 5, 1957, Serial No. 682,239

6 Claims. (Cl. 22-42) This invention relates to molding press headcontrol systems wherein a flexible diaphragm is expanded by applyingfluid pressure behind diaphragm to pack sand within a mold flask, andmore particularly to an improved control apparatus for retracting thediaphragm away from the sand after the sand has been packed within theflask.

The usual arrangement in systems of this type is to employ a hollow,boxlike mold press head, the lower wall of which is defined by aflexible rubber diaphragm. The press head is mounted in a fixedposition, and molding flasks which have been filled with sand arebrought into position beneath the mold head by a conveyor systern (notshown). By supplying fluid under pressure to the interior of the presshead, the flexible diaphragm is expanded into contact with the sand inthe flask and further application of pressure to the interior of thepress head causes the diaphragm to firmly compact the sand within theflask. When the sand has been compacted, the pressure source isdisconnected from the press head and a vacuum source is connected toexhaust the fluid from the interior of the head, thus retracting thediaphragm away from the sand within the flask to permit the flask to bemoved away from the mold head.

In the usual case, the vacuum source takes the form of a pump which,because of the relatively rapid rate at which flasks are presented tothe press head, is continuously operated or driven. Because of therelatively high pressures employed in compacting the sand within themold flask, it has been found that when the vacuum pump is firstconnected to the press head, the capacity of the pump is insuflicient tohandle the amount of pressurized air flowing from the press head andthus actually impedes the initial flow of high pressure air from thepress head. Since molding apparatus of this general type is usuallyoperated at a full capacity basis, the cumulative delays occasioned bythe inability of the vacuum pump to handle the necessary flow of airfrom the pressure head become quite substantial.

The primary object of my invention is to provide a means for increasingthe productive capacity of molding apparatus of the type describedabove.

Another object of my invention is to provide a molding press headcontrol system in which the speed of retraction of the flexiblediaphragm may be increased without increasing the capacity of the vacuumpump employed to retract the diaphragm.

Still another object of my invention is to provide means for improvingthe efliciency of the vacuum pump employed in a molding apparatus of thetype described above which may be easily installed on existing equipment.

Other objects and advantages of my invention will become readilyapparent by reference to the following specification taken inconjunction with the accompanying drawings.

In the drawings: Figure l is a partially schematic view of a moldingpress head, shown in cross-section, embodying my invention;

Figure 2 is an end view of the vacuum pump and as sociated ducts of Fig.1;

Figure 3 is a plan view of the valve of Fig. 2;

Figure 4 is a partial cross-sectional view taken on the line of 44 ofFig. 2. Y

Referring first to Fig. l, a mold press head designated generally 10includes a boxlike metallic frame 12 having a flexible rubber diaphragm14 sealingly secured across the open lower side of the frame. While thepress head assembly 10 is shown only in cross-section, it is believedapparent that the flexible diaphragm 14 defines the lower wall of aclosed chamber within the head 10.

A duct 16 is connected to openings through the frame 12 as at 18 and 20and connects the interior of the chamber 15 to one port of aschematically illustrated valve 22; A pressure source 24 is connected tothe valve 22 by' means of a'duct 26 to supply pressure through the duct16 to the chamber 15 when the movable member of the.

valve 22 is in the position shown in Fig. l.

A vacuum pump 28 is connected to the valve 22 through a duct 30. It isbelieved apparent that the movable member of valve 22 may be rotatedthrough a ninetydegree angle from the position shown in Fig. 1 to con-inect the duct 30 to the duct 16 thereby connecting" the chamber 15 tothe vacuum pump 28.

.Pump 28 is of conventional construction, and may conveniently be of thecentrifugal type in which the impeller is driven by means of a shaft 32driven by a conventional motor (not shown). The normalinlet open ing 34of the pump 28 is covered by a plate 36 having a reduced diameter inletopening 38. An inlet duct assembly 40 includes a flange 42 whichoverlies the plate 36 and is secured to the frame of the pump 28 bymeans' of bolts 44 which clamp the plate 36 into sealing engage mentwith the pump casing. As best seen in Fig. 2, the inlet duct assembly 40includes coaxially arranged outer 46 and inner 48 ducts. At its lowerend, the outer duct,

46 is connected as by welding to a duct section 50 which is providedwith a flange 52 for connection to a corresponding flange on the endofthe duct 30. The inner duct 48 extends across the interior of the ductsection 50 and is mounted withinthe outer duct 46 by welding the lowerend of the duct-48 to the interior of the duct section 50. Duct 48 is sodimensioned that when the duct assembly 40 is mounted on the pump frame,the upper end of the inner duct 48 surrounds the opening 38 in plate 36and effectively seals this end of the duct- 48 to the plate 36. At itslower end, the inner duct' 48 is provided with a pair of relativelysmall orre-- stricted inlet openings 54 placing the duct 48 in communication with the ducts 46 and 50.

A venting duct 56 is secured, as by welding, to the outer duct 46 and isin open communication with the, interior of the outer duct. At its upperend, the venting" duct is provided with a flap valve assembly 57 whichincludes a flap 58 which is supported upon a pivot pin 60 journaled intoa lug 62 fixed to the upper end of duct 56. a The lower surface of theplate-58 is provided with a rubber face 64 to improve the sealingcharacthe valve 22 is actuated to the position shown in Fig. 1 to.connect the pressure source 24 to the chamber 15. Fluid under pressureenters the chamber and expands the flexible diaphragm into engagementwith the sand, and as further pressure is supplied to the chamber 15,the flexible diaphragm 14 compacts the sand within the flask F about thepattern P.

After a predetermined pressure has been achieved Within the chamber 15,the valve 22 is actuated to disconnect pressure source 24 from thechamber 15 and connect the chamber 15 to the duct Fluid under pressurepasses from chamber 15 into the duct 30 and into the interior of theduct section 50. From the duct section 50, the fluid under pressure mayflow into the interior of both ducts 46 and 48. When the pressure withinthe duct 46 begins to rise due to the flow of pressurized air from thepress head, plate 58 of the flap valve is moved upwardly into the dottedline position of Fig. 2, thereby opening the interior of the duct 46 tothe atmosphere through the duct 56. In this manner, the pressure withinchamber 15 is rapidly reduced to atmospheric pressure.

As disclosed in the drawings, plate 58 is gravitationally biased towardits closed position, and when the pressure within the chamber 15, andhence ducts 30, 50, and 46 approaches atmospheric pressure, the flapvalve automatically closes by the fall of plate 58 to its full lineposition in Fig. 2. In certain applications, it may be desirable to usea spring biased valve closure member. After the valve 57 closes, theconstantly driven vacuum pump 28 continues to reduce the pressure withinchamber 15 to below atmospheric pressure and thereby retracts theflexible diaphragm 14 upwardly away from the sand within the flask F.When the diaphragm is retracted, the traverse car T- containing thecompacted mold flask is removed and a fresh traverse car T is moved intoposition beneath the press head 10 fora repetition of the foregoingoperation.

Since the vacuum pump 28is constantly driven, it can be appreciated thatthe foregoing operation may be rapidly repeated. The rapid lowering ofthe pressure within chamber 15 by venting this chamber to the atmospherethrough the outer duct 46, duct 56 and the flap valve permits-thepressure within chamber 15 to be rapidly reduced below atmosphericwithout: requiring a substantial increase in the capacity of the vacuumpump 28.

While I have described butone embodiment of my invention,'itwill beapparent-to those skilled in the art that the disclosed embodimentiscapable of modification. Therefore, the foregoing description is to beconsidered exemplary rather than limiting and the true scope ofmyinvention is that defined in the following claims.

I claim:

1. In combination with a mold press head having pressure responsivemeans for compacting sand within a mold flask; a pressure source formoving said pressure responsive means to a sand compacting position andincluding a first duct means, a vacuum source for retracting saidpressure responsive means from said sand compacting position andincluding a second duct means, valve means for selectively connectingeither said first or said second duct means to said press head, andmeans for venting said second duct means to atmospheric pressure whenthe pressure in said second duct exceeds a predetermined pressure.

2. In combination with a mold press head having pressure responsivemeans for compacting sand within a-mold flask; a pressure source formoving said pressure responsive means to a sand compacting position andincluding a first duct means, a vacuum source for retracting saidpressure responsive means from said sand compacting position andincluding a second duct means, valve means for selectively connectingeither said first or said second duct means to said press head, a valvein said second duct means for venting said second duct means toatmospheric pressure, and means for closing said valve when the pressurein said second duct means approaches atmospheric pressure.

3. The combination recited in claim 2 wherein said second duct meansincludes an inner duct connected to said vacuum source, an outer duct incommunication with said inner duct, and means connecting said valve tosaid outer duct.

4. In combination with a mold press head having pressure responsivemeans for compacting sand within a mold flask; a pressure source formoving said pressure rcsponsive means to a sand compacting position andincluding a first duct means, a constantly driven vacuum pump forretracting said pressure responsive means from said sand compactingposition, second duct means connected to the inlet of said vacuum pump,valve means for selectively connecting either of said first and saidsecond duct means to said press head to operate said pressure responsivemeans, and means for venting said second duct means to atmosphericpressure when the pressure in said second duct exceeds a selectedpressure.

5. In combination with a mold press head having pressure responsivemeans for compacting sand Within a mold flask; a pressure source formoving said pressure responsive means to a sand compacting position andincluding a first duct means, a constantly driven vacuum pump forretracting said pressure responsive means from said sand compactingposition, second duct means connected to the inlet of said vacuum pump,valve means for selectively connecting either of said first and said'second duct means to said press head to operate said pressureresponsive means, a valve in said second duct means for venting saidsecond duct means to atmospheric pressure, and means for closing saidvalve when the pressure in said second duct means approaches atmosphericpressure.

6. In combination with a mold press head having pressure responsivemeans for compacting sand within a mold flask; a pressure source formoving said pressure responsive means to a sand compacting position andincluding a first duct means, a constantly driven vacuum pump forretracting said pressure responsive means from said 'sandcompactingposition, an inner duct connected to the inlet of said vacuum pump, anouter duct surrounding said inner duct and in communication there with,a normally closed valve mounted on said outer duct for venting saidouter duct to atmospheric pressure, and means for opening said valvewhen the pressure Within said outer duct is above a predeterminedpressure.

References Cited in the file of this patent UNITED STATES PATENTS2,715,758 Taccone Aug. 23, 1955 2,767,445 Taccone Oct. 23, 19562,805,455 Whitesell Sept. 10, 1957 FOREIGN PATENTS 682,295 France Feb.11, 1930 788,955 France Aug. 5, 1935

